1. Field
The following description relates to an apparatus and method for transmitting data to a relay for forwarding received data to a data receiving apparatus and a method for forwarding data.
2. Description of Related Art
Recently active research is being conducted in wireless communications for the purpose of providing various multimedia services, including voice service, and supporting high quality and high speed data transmission. As a part of those studies, there have been significant developments in the techniques related to a multiple input multiple output (MIMO) communication system using spatial channels.
MIMO techniques utilize multiple antennas that provide high data transmission rates by increasing a channel capacity within limited frequency resources. MIMO techniques use multiple transmission and receiving antennas in a channel environment enriched with scattering objects. Conceptually, MIMO techniques are capable of providing channel capacity enhancements proportional to the number of antennas with fewer quantities between receiving antennas and transmission antennas.
To expand the coverage of a specific base station, there is active research in techniques utilizing relays. Terminals make connections to the relays, and the relays transmit data to a base station after receiving the data from the terminals.
However, when relays are included in a communication system, wireless resources are required for the relays, such as time slots and the like. As an example, assume that a relay operates between a base station and a terminal. The base station transmits a message A to a relay during a time slot T1 (which is one of the downlink time slots), and a terminal transmits a message B during a time slot T2, (which is one of uplink time slots). In this instance, the relay transmits the message A to the terminal during a time slot T3, which is one of the downlink time slots, and transmits the message B to the base station during the time slot T4, which is one of uplink time slots.
In the above described example, to transmit the message A from the base station to the terminal via the relay and to transmit the message B from the relay to the base station, at least 4 time slots are utilized, such as T1, T2, T3, and T4. When the base station and the terminal directly transmit and receive the messages A and B without using the relay, only two time slots are utilized. Therefore, it appears as though more wireless resources are consumed when relays are added to a communication system.
Consequently, a technique which may maximize a data transmission rate by reducing consumption of wireless resources, such as time slots, even when adding relays in a communication system may be desired.